MOS field-effect transistors with very thin silicon dioxide based gate dielectrics may experience unacceptable gate leakage currents. Forming the gate dielectric from certain high-k dielectric materials, instead of silicon dioxide, can reduce gate leakage. When conventional processes are used to deposit a high-k gate dielectric on a silicon substrate, a silicon dioxide transition layer may form between the dielectric and the substrate. The presence of that transition layer may contribute to the overall electrical thickness of the gate dielectric stack. As devices continue to shrink, it may be desirable to decrease the electrical thickness by eliminating that transition layer.
Accordingly, there is a need for an improved process for making a semiconductor device that includes a high-k gate dielectric. There is a need for a process for forming such a device that eliminates the silicon dioxide transition layer, which forms when a high-k gate dielectric is deposited on an underlying silicon substrate. The method of the present invention provides such a process.
Features shown in these figures are not intended to be drawn to scale.